The present invention relates to systems for importing, storing, and vaporizing liquified natural gas (LNG).
There currently exist only about four import terminal facilities in the United States for receiving LNG. At these facilities, the LNG is unloaded from LNG tankers and stored in land-based, insulated tanks. From these tanks the LNG is typically pumped through a heated vaporizing system for delivery as a gas to a gas pipeline distribution system.
Natural gas prices are currently increasing rapidly due to inability to meet demand. Unfortunately, the LNG import terminals existing in the United States are presently operating at capacity. New import terminals of the type currently used in the United States cost hundreds of millions of dollars to build. Moreover, it is very difficult and expensive to find and acquire permissible sites for such facilities. Besides the space needed for the import tanks, pumps, vaporizers, etc., large impoundment safety areas must also be provided around all above-ground LNG storage and handling vessels and equipment. LNG import facilities also consume large amounts of fuel gas and/or electrical energy for pumping the LNG from storage and vaporizing the material for delivery to gas distribution systems.
Thus, a need presently exists for LNG import, storage, vaporization, and delivery systems which are more energy efficient and are less difficult and expensive to site and build. In view of the urgent need for additional import capacity in the United States, the new import, storage and delivery facilities will also preferably be able to be placed in operation very quickly.
The present invention satisfies the needs and alleviates the problems discussed hereinabove. The inventive system can generally be used for receiving, storing, vaporizing, and delivering LNG from any source. The inventive system is particularly well-suited for receiving LNG from tankers, ships, or any other types of marine transport vessels.
In one aspect, the present invention provides a method of handling liquified natural gas (LNG) comprising the steps of: (a) delivering the LNG in a liquid state into a subterranean formation such that the LNG absorbs heat energy from the subterranean formation which converts the LNG to a gas product in the subterranean formation and (b) producing the gas product from the subterranean formation.
The subterranean formation will preferably be a gas formation which has been substantially depleted. The conversion of the LNG to gas in the subterranean formation will preferably increase the formation pressure sufficiently at least for producing the gas from the formation. Once produced from the formation, the gas will preferably be conducted to a desired delivery point. Examples of typical delivery points could include, but are not limited to, gas pipeline systems or gas-burning facilities.
In another aspect, the present invention provides a method of handling LNG comprising the steps of (a) unloading the LNG from a marine transport vessel at an offshore receiving station and (b) delivering the LNG into an offshore subterranean formation such that the LNG absorbs heat energy from the formation which converts the LNG to a gas product. The offshore subterranean formation will preferably have at least one well extending into the formation via which the LNG is delivered in step (b). The method preferably further comprises the steps of: (c) producing the gas product from the offshore formation; and (d) conducting the gas product to a land-based receiving point. The conversion of the LNG to gas in step (b) will preferably increase the pressure of the offshore subterranean gas formation such that the formation pressure is sufficient at least for producing the gas from the formation.
In yet another aspect, the present invention provides an apparatus for handling LNG. The inventive apparatus preferably comprises: an offshore receiving station for receiving LNG from a marine transport vessel; an offshore gas production platform for producing gas from a subterranean gas formation, the subterranean gas formation having at least one well extending thereinto; means for delivering the LNG received from the marine transport vessel into the well; and means for conducting gas from the offshore subterranean gas formation to a land-based receiving point.
Further objects, features and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following description of the preferred embodiments.